1. Field of the Invention
The present invention relates to a printer that executes a printing process based on commands and other data received from a host device, and relates specifically to a printer that interrupts the printing process until consumable materials that have been depleted are replenished and then executes a resume-printing process.
2. Description of the Related Art
The standard configuration for the data input/output device, host device, and printer in the point of sale or POS/ECR field has conventionally been an integrated, stand-alone system. In more recent years, however, faster data processing and more flexible system architectures have led to the development and wide-spread acceptance of distributed systems in which the data input/output device, host device, and printer are separated from each other and can be used in separate locations.
The printers used in such distributed systems are generally called "terminal printers." An example of a POS/ECR system using such a terminal printer in a restaurant or other food service business is described below.
The printer used in this application is called a "kitchen printer." When the waiter or waitress receives a customer order and enters the order to a hand-held data entry device, the order is transmitted immediately to a host device and printed to hard copy by the kitchen printer located in the kitchen. This system helps prevent errors because the operator can process the information while viewing the print content, thereby facilitating the management and processing of goods sold. These benefits have led the way to similar systems being introduced in a variety of businesses.
It is often the case, however, that cooking appliances, safes, or other relatively more important equipment be given priority in selecting installation space. This has increased demand for compact printers with a small footprint and space requirements, and compact printer designs necessarily limit the on-line availability of consumable printing materials, i.e., the size of the paper rolls that can be installed and the amount of ink in the ink cartridges. The host device is also usually located in a separate place due to restrictions in the operating environment. In addition, the printer typically prints large volumes of information, frequently resulting in consumable printer supplies being depleted while the system is in use.
The amount of paper that is left on the roll is detected using a paper-out sensor that detects when there is no more paper on the roll and a near-end sensor that detects when there is little paper left on the roll; and the amount of remaining ink left in the ink cartridge can be likewise monitored using a remaining-ink detector. When these consumable materials are depleted, the printing process is immediately stopped and the printer enters an off-line state in which additional print data cannot be received by the printer or storage of print data transferred to the printer is not assured. Loss of data sent from the host device is prevented in this case by notifying the host device that the printer is off-line.
When the host device is notified that the printer is off-line, an indicator is flashed or a buzzer is sounded to notify the operator that some or all consumable materials need replenishing. Once the consumable materials have been replenished, an on-line switch is pressed either intentionally, by closing the roll paper cover or ink cartridge cover to notify the host device that the printer is again on-line and printing can be resumed. More specifically, the operator must restore the printer to the on-line state and resume the printing process after adding roll paper or replacing the ink cartridge by manually operating an on-line switch. Alternatively, when one of the above covers is closed after replenishing the consumable materials, a cover sensor can detect that the cover is closed, restore the printer to the on-line state, and thereby enable resumption of the printing process.
When the roll paper is replaced it may also be necessary for the operator to operate a paper feed switch to advance a torn or discolored roll paper leader before resetting the printer to the on-line state by operating the on-line switch. Depending upon the type of ink cartridge used, ink build-up around the ink nozzles from which the ink is ejected may cause failure in ink ejection. In such cases the operator must operate a switch after installing a new ink cartridge to flush out any ink build-up, and then restore the printer to the on-line state by means of the operation described above.
While the above examples specifically address roll paper and ink cartridge depletion, similar problems occur with conventional thermal transfer printers that use a consumable ink ribbon. When the ink ribbon is depleted or nearly depleted, the printer goes off-line, and the operator must replace the ribbon and then restore the printer to the on-line state by means of an operation as described above.
At the same time, however, demand for low cost and high reliability have driven the need to reduce the number of parts and components while maintaining functionality. This has led to a reassessment of the need for cover sensors and dedicated on-line switches as used for the operations described above.
A technology for eliminating such on-line switches and cover sensors has been disclosed in Japanese laid-open patent number H6-47992 (47992/94-). The method of this technology assumes that the ink or other consumable material is replenished within a known predefined period after the printer goes off-line, and automatically restores the on-line status when this period is up.
The problem with this method is that the actual time required to replace the roll paper or other consumable materials varies according to the operator and the operator's familiarity with the printer, and it may be necessary or desirable to replace plural consumable materials at the same time, e.g., replace the ink cartridge at the same time as the roll paper. As a result, it may not always be possible to resume printing within a constant period of time. If printing is resumed before printing is actually possible, the information will not be correctly printed and print data may be lost. If this method is implemented with a kitchen printer as described above or cash register, loss of print data can result in business disruptions and problems.